Effects Of Swine Manure On Antibiotic Resistance Genes In Rhizosphere

As a novel emergencing environmental pollutant,antibiotic resistance genes(ARGs)has attracted extensive attention in the past ten years,because it can lead to drug-resistant bacterial infection can not be treated,and pose a great threat to human health.The extensive use of antibiotics in animal husbandry will accelerate the enrichment of antibiotic resistance genes in the surrounding environment.The application of animal manure as organic fertilizer is one of the major pathways for antibiotic resistance genes to enter the environment.Moreover,the mobile genetic elements(MGEs)carried by swine manure contribute to the transmission and diffusion of antibiotic resistance genes.The increase of ARGs in plant(vegetable)rhizosphere environment caused by swine manure application will directly threaten human health through the food chain.In this study,a root-box pot experiment was designed to detect the changes of antibiotic resistance genes in rhizosphere soil by high-throughput quantitative PCR and the effect of pig manure application on soil microbial community by high-throughput sequencing.In order to provide a theoretical basis for the ecological risk assessment of pig manure in the process of agriculture.In this study,three treatments(BS,BM and SM)were set up,each with three repeats,and soil samples were collected at 0d,15 d,30 d and 60 d after seeding,respectively,for follow-up experiments.In this study,a total of 209 genes were detected,including 198 ARGs(aminoglycosides 31,β-lactams 37,FCA 11,MLSB 32,multidrug resistance 28,sulfonamides 2,tetracyclines 35,vancomycin 9).10 MGEs(one IS,two integrons and seven transposons)and 1 bacterial 16 s rRNA gene.The amount of ARGs in the soil with pig manure(SM,107)was higher than that in the original soil(BM,41),and the relative abundance of total ARGs was also significantly higher.The relative abundance of total ARGs in rhizosphere soil was lower than that in non-rhizosphere soil after pig manure was applied.The amount and relative abundance of ARGs in soil decreased with time from the application of pig manure to the end of the experiment.There was a positive correlation between the relative abundance of total MGEs and the relative abundance of total ARGs,which indicated that the potential horizontal transfer of ARGs was more likely.The copy number of bacteria and fungi increased with the application of pig manure,but the sequencing results showed that the α diversity of bacteria and fungi in the soil decreased significantly after the application of pig manure,and increased with the passage of time.The application of pig manure significantly changed the community structure of bacteria and fungi in the soil and significantly increased the relative abundance of Firmicutes and Sordariomycetes in the soil.Correlation analysis showed that there was a significant positive correlation between bacterial fungal abundance and total ARGs relative abundance,but a negative correlation between their Shannon Wiener index and total ARGs.Network analysis showed that Firmicutes may be the main host of most of the detected ARGs.